Granular calcium hypochlorite treatment process

Abstract

A method for preparing granular calcium hypochlorite treated with polyfluorinated polymer is disclosed. The treated product may be compressed and formed into shaped articles. A method described comprises spraying a suspension of polyfluorinated polymer, e.g., polytetrafluoroethylene, onto granular calcium hypochlorite in a continuous or batch blender. Tablets prepared from the granular hypochlorite so surface treated with polyfluorinated polymer dissolve in water at a rate slower than tablets prepared from granular calcium hypochlorite having polyfluorinated polymer dispersed throughout the granules. Granular calcium hypochlorite having a particle size range of -6, +100 U.S. Sieve Series having from about 0.005 to 0.5 weight percent polyfluorinated polymer on its surface are described.

We claim: 
     
       1. A method for preparing calcium hypochlorite articles for use in slow dissolving applications, comprising treating the surface of granular calcium hypochlorite having a principal particle size range of between -6 and +100 U.S. Sieve Series with from about 0.005 to about 0.5 weight percent of an agent consisting essentially of polyfluorinated polymer, and forming said treated granular hypochlorite into a shaped article having a mass of between about 1 gram and about 350 grams. 
     
     
       2. The method of claim 1 wherein the polyfluorinated polymer is a polytetrafluoroethylene. 
     
     
       3. The method of claim 2 wherein the polyfluorinated polymer is unfibrillated. 
     
     
       4. The method of claim 2 wherein the shaped article is in the form of a tablet. 
     
     
       5. The method of claim 2 wherein the surface of the granular calcium is treated with from about 0.05 to about 0.35 weight percent of polytetrafluoroethylene. 
     
     
       6. The method of claim 5 wherein the polytetrafluoroethylene is unfibrillated. 
     
     
       7. The method of claim 6 wherein the shaped article is in the form of a tablet having a mass of between about 7 grams and 300 grams. 
     
     
       8. The method of claim 1 wherein the granular calcium hypochlorite is treated by spraying an aqueous suspension of the polyfluorinated polymer onto a bed of agitated calcium hypochlorite granules. 
     
     
       9. The method of claim 8 wherein the polyfluorinated polymer is polytetrafluoroethylene. 
     
     
       10. Granular calcium hypochlorite having a principal particle size range between -6 and +100 U.S. Sieve Series having from about 0.005 to about 0.5 weight percent of an agent consisting essentially of polyfluorinated polymer applied to the surface of the granules, the interior of said granules being substantially free of said polyfluorinated polymer. 
     
     
       11. Granular calcium hypochlorite according to claim 10 wherein the polyfluorinated polymer is polytetrafluoroethylene. 
     
     
       12. Granular calcium hypochlorite according to claim 11 wherein from 0.05 to 0.35 weight percent of polyfluorinated polymer is applied to the surface of the granules. 
     
     
       13. Granular calcium hypochlorite according to claim 11 wherein the polyfluorinated polymer is unfibrillated. 
     
     
       14. A solid calcium hypochlorite article prepared from the calcium hypochlorite granules of claim 10, said article having a mass of between about 1 gram and about 350 grams. 
     
     
       15. The solid calcium hypochlorite article of claim 14 which is in the form of a tablet having a mass of between about 7 and about 300 grams.